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BMC Clinical Pathology 2001, 1:5
doi:10.1186/1472-6890-1-5

Published: 16 October 2001

Abstract

Background

Reliability cannot be achieved in a clinical laboratory through the control of accuracy
in the analytical phase of the testing process alone. Indeed a "mistake" can be defined
as any defect occuring during the testing process. In the analysis of clinical specimens,
there are many possible preanalytical sources of error. Therefore, the application
of quality system to laboratory testing requires total quality management throughout
the laboratory process, including the preanalytical and postanalytical phases. ISO
9002:1994 is a model for quality assurance in production, installation, and servicing,
which includes a number of clauses providing guidance for implementation in clinical
laboratories. Our laboratory at King Chulalongkorn Memorial Hospital, the largest
Thai Red Cross Society hospital, is the first clinical laboratory in Thailand with
ISO 9002:1994 certified for the whole unit.

Method

In this study, we evaluated the frequency and types of preanalytical mistakes found
in our laboratory, by monitoring specimens requested for laboratory analyses from
both in-patient and out-patient divisions for 6 months.

Result

Among a total of 935,896 specimens for 941,902 analyses, 1,048 findings were confirmed
as preanalytical mistakes; this was a relative frequency of 0.11 % (1,048/935,896).
A total of 1,240 mistakes were identified during the study period. Comparing the preanalytical
mistakes to other mistakes in the laboratory process monitored in the same setting
and period, the distribution of mistakes was: preanalytical 84.52 % (1,048 mistakes),
analytical 4.35 % (54 mistakes), and postanalytical 11.13 % (138 mistakes). Of 1,048
preanalytical mistakes, 998 (95.2%) originated in the care units. All preanalytical
mistakes, except for 12 (1.15 %) relating to the laboratory barcode reading machine,
were due to human error.

Conclusion

Most mistakes occurred before samples were analysed, either during sampling or preparation
for analysis. This suggests that co-operation with clinicians and personnel outside
the laboratory is still the key to improvement of laboratory quality.